Molecular pathways: epigenetic modulation of Wnt-glycogen synthase kinase-3 signaling to target human cancer stem cells.

Aberrant regulation of the canonical Wnt signaling pathway (Wnt-β-catenin-GSK3 axis) has been a prevalent theme in cancer biology since earlier observations until recent genetic discoveries gleaned from tumor genome sequencing. During the last few decades, a large body of work demonstrated the involvement of the Wnt-β-catenin-GSK3 signaling axis in the formation and maintenance of cancer stem cells (CSC) responsible for tumor growth in several types of human malignancies. Recent studies have elucidated epigenetic mechanisms that control pluripotency and stemness, and allow a first assessment on how embryonic and normal tissue stem cells are dysregulated in cancer to give rise to CSCs, and how canonical Wnt signaling might be involved. Here, we review emerging concepts highlighting the critical role of epigenetics in CSC development through abnormal canonical Wnt signaling. Finally, we refer to the characterization of novel and powerful inhibitors of chromatin organization machinery that, in turn, restore the Wnt-β-catenin-GSK3 signaling axis in malignant cells, and describe attempts/relevance to bring these compounds into preclinical and clinical studies. ©2014 American Association for Cancer Research.